Drum type magnetic separator



A g; 23, 1960 w. BUUS x I 2,950,008

DRUM TYPE MAGNETIC SEPARATOR f 2 Sheets-Sheet l Filed May 1a, 1956 A g 23,1960; Htwiuus 2,950,008

-- -DRUM TYPE MAGNETIC SEPARATOR Filed May 18,1956

2 Sheets-Sheet 2 INVENTOR. #22040 14 fiuus United States Patent DRUM TYPE MAGNETIC SEPARATOR Harold W. Buns, Hales Corners, Wis, assignor, by mesne assignments, to Indiana General Corporation, a corporation of Indiana Filed May 18, 1956, Ser. No. 585,729

4 Claims. (Cl. 209-219) This invention relates to a drum type magnetic separator. In such a separator, the material to be separated is fed over the periphery of a drum which is rotating about stationary magnets. Relatively non-magnetic material falls freely from the drum while relatively magnetic material clings to the periphery of the drum for a period sufficiently so that it moves across a stationary divider separating it from the non-magnetic material.

As compared with existing separators of this type, I am able to achieve a greatly superior separation with much less power on the electro magnets and greatly increased depth of field by the structure of the present invention.

The stationary stub shafts which carry the magnetic core are so mounted that the drum hubs can rotate upon them. Within the drum, the shafts are connected by a plate of magnetic material which extends longitudinally of the drum, but is offset from the center thereof. The polar core or cores which carry the windings are mounted on this plate and extend diametrically across the axis of the drum to the periphery thereof remote from the plate. Here they carry arcuate polar members in close proximity to the inner periphery of the drum except at their ends toward which the drum rotates. These desirably deviate progressively from the drum periphery. Other polar cores, not provided with windings, may respectively be mounted on the stub shafts which carry the plate aforesaid and, assuming that there are two or more wound cores, an intermediate unwound core may be mounted on the plate between those cores which are wound.

The polar structure provides a wide open rectangular rame for the flux path, the frame desirably being elongated longitudinally of the drum and providing as much space as possible for the windings. The latter desirably taper outwardly of their respective cores in order that the reduced outer ends of the windings may be received within the arcuate poles. The cores themselves are desirably rectangular in cross section.

The drum itself is novel in that it comprises two concentric peripheral plies which provide an unusual degree of strength to support the material passing over the periphery of the drum and yet permits of ready replacement of the exposed ply in the event of damage thereto. This desirable structure is made possible because of the unusual depth of field resulting from the arrangement and the winding of the cores.

In the drawings:

Fig. 1 is a view in perspective of a device embodying the invention, portions of the drum being broken away to expose the interior core and winding structure.

Fig. 2 is a view of the device on a reduced scale in longitudinal section on the line 2-2 of Fig. 3.

Fig. 3 is a view taken in section on line 33 of Fig. 2.

Fig. 4 is a chart showing the field strength.

The stub shafts 5 and 6 are supported in any appropriate mountings 7 and 8, respectively, and fixed against rotation. The drum heads 9 and 10 have hub portions supported by bearings 11 and 12 from these shafts. The drum comprises concentric inner and outer shells 13 and 14 supported on flanges 15 and 16 of the respective heads to provide a two ply periphery for the drum beyond which the heads desirably extend to confine to the face of the drum the material fed thereover for separation. Drum heads 9 and "10 and inner and outer shells 13 and 14 are conveniently made of non-magnetic material.

Any appropriate means may be used for rotating the drum as, for example, a sprocket 17 attached to the hub of head 10 and driven by a chain 18.

Mounted on the stub shafts 7 and 8 within the drum is a heavy plate at 20 which forms a part of the flux path. The plate 20 is bolted to the stub shafts at one side of the axis.

Connected to the plate 20 and extending across the axis toward the opposite side of the drum are the cores 21 and 22 upon which the windings 23 and 24 are respectively mounted. These cores are not round but are very considerably elongated rectangularly in a direction at right angles to the axis of the drum as clearly appears in Fig. 1. By reason of this transverse elongation of the cores, and the dropped or off center support therefor on the plate 20, the amount of magnetic steel which can be incorporated is greatly increased with corresponding increase in the efiectiveness of the electromagnet. The windings 23 and 24, instead of being generally cylindrical, are likewise rectangular and transversely elongated as clearly appears in Fig. l. The windings are confined between metal magnet heads 25 and 26 which are welded or otherwise fastened to the respective magnet cores 21 and 22. The winding is such that at the outer ends of the respective windings 23 and 24 the windings are very sharply tapered in the manner shown at 27. At their reduced ends where the windings abut the magnet heads 26, there is barely clearance for the windings within the arcuate polar bars 29 and 30 which cap the cores 21, 22, respectively, and are bolted thereto. These bars are in immediate proximity to the inner shell 13 of the drum except at the ends of the poles toward which the drum rotates. At this end, each polar bar is curved inwardly away from the inner periphery of the drum as shown at 31 in Fig. 3, the direction of drum rotation being clockwise as viewed in that figure.

Unwound poles 32 and 3 3- are mounted on the stub shafts 5 and 6 in the form of plates of peripheral extent and marginal outline corresponding to the polar bars 29 and 30. A much heavier unwound pole 35 of similar extent and peripheral outline is mounted at the center of the frame plate 20 between the wound poles 21 and 22 as best shown in Figs. 1 and 2. The windings and their connections are desirably such that the polar cores 21 and 22 and the polar bars 29 and 30 mounted thereon are of like polarity. Assuming that the polar bars 29 and 30 are north poles, the peripheral margins of the unwound poles 32, 33 and 35 will all be south poles.

Wiring connections at 38 may be provided toreach the windings to energize the electro magnets through a bore or bores at 30 in one or both of the stub shafts 5 or 6.

My construction provides a very powerful and Well distributed magnetic field as shown by the diagram included in Fig. 4-. Notwithstanding the use of a dual shell drum, it will be observed that a magnetic field of 1000 gauss was found to exist at a radius of one to two inches beyond the drum periphery. The field measured 500 gauss at a radius of two to five inches outside of the drum periphery, and 300 gauss, four to seven inches beyond the drum periphery. As compared with a widely used and favorably known prior art drum type separator or" identical dimensions, my improved separator shows an extraordinary increase in field strength. The prior art separator showed no areas of 1000 gauss except for a fraction of an inch immediately over each pole. In the old separator the depth of the 500 gauss field nowhere exceeded two inches and the 300 gauss field only slightly exceeded'three inches, and this at only two points.

Yet the magnet herein disclosed utilizes only about onehalf of the amount of copper wire used in the older conventional structure.

In operation, the material to be separated is discharged down a chute 40 onto the periphery of the outer rotating shell 14. The plate 20 and the magnets are tilted from the vertical in the manner shown in Fig. 3 so that the material to be separated reaches the periphery of the drum near the point at which it encounters the beginning of the magnetic field produced by the poles. The nonmagnetic material falls from the periphery of the drum at 41 at the right of the separating baflle 42 while the magnetic material falls at 43 at the left of the baffie.

, The increased effectiveness of this drum type separator is such as to adapt it for the most exacting separating tasks. Because the magnetic poles are relatively close to the material, this type of separator tends to be more effective than a pulley type separator in which a belt necessarily intervenes. In addition to routine separating tasks, the greater efiectiveness of this separator adapts it to separation of residual iron from slag piles, thus recovering metal which has heretofore been deemed beyond recovery. For this kind of heavy Work, the two ply drum periphery is a particularly valuable feature because of the ease with which the outer ply can be replaced when worn or damaged. Moreover, the outer ply of the drum periphery can be made of material which is abrasion resistant, regardless of strength, the inner ply being relied upon for strength. Thus, the outer ply may be nonmetallic material such as rubber or canvas, as desired.

One of the reasons for the very powerful and deep magnetic field is the fact that there is little or no leakage of magnetic flux, substantially all of the flux developed being concentrated at the poles and in the separation zone. The strength and depth of the field make it possible for many of the advantages of the invention to be achieved by using the drum as a pulley over which a belt is operated. However, maximum advantage of the construction cannot be achieved except in a drum type separator for which the core frame and poles and windings have been particularly designed.

I claim:

1. In a magnetic separator, a rotatable drum for receiving material to be separated at the top portion thereof and for retaining magnetic material therewith beyond the point where non-magnetic material falls from the drum, a wound magnetic core member extending generally radially of said drum and having an end terminating close to the drum perpihery, a winding on said wound core member, an aruate polar bar secured to said end of said wound core member with an outer end face of said polar bar extending in close relation to the interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said polar bar extending peripherally beyond said wound core member on each side thereof, and non-wound magnetic core members extending generally radially of said drum and disposed adjacent opopsite sides of said wound core member along the axis of said drum, said nonwound magnetic core members each having a radially outer end with an arcuate end face in close relation to the interior surface of the drum and extending along said interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said non-wound core members each having at the radially outer end thereof a circumferential dimension in the direction arcuately about the drum axis which greatly exceeds the corresponding dimensions of said wound core member over a radial depth of each non-wound core member inwardly from the arcuate end face thereof greatly exceeding the radial depth of said polar bar.

2. In a magnetic separator, a rotatable drum for receiving material to be separated at the top portion thereof and for retaining magnetic material therewith beyond the point where non-magnetic material falls from the drum, a pair of wound magnetic core members extending generally radially of said drum and each having an end terminating close to the drum periphery, a winding on each of said wound core members, an arcuate polar bar secured to said end of each of said wound core members with an outer end face of said polar bar extending in close relation to the interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said polar bars extending peripherally beyond said wound core members on each side thereof, and non-wound magnetic core members extending generally radially of said drum and disposed alternately with said wound core members along the axis of said drum, said non-wound magnetic core members each having a radially outer end with an arcuate end face in close relation to the interior surface of the drumand extending along said interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said non-wound core members each having at the radially outer end thereof a circumferential dimension in the direction arcuately about the drum axis which greatly exceeds the corresponding dimension of each of said wound core members over a radial depth of each non-Wound core member inwardly from the arcuate end face thereof greatly exceeding the radial depth of said polar bars.

3. In a magnetic separator, a rotatable drum for receiving material to be separated at the top portion there of and for retaining magnetic material therewith beyond the point where non-magnetic material falls from the drum, a wound magnetic core member extending generally radially of said drum and having an end terminating close to the drum periphery, a winding on said wound core member, an arcuate polar bar secured to said end of said wound core member with an outer end face of said polar bar extending in close relation to the interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said polar bar extending peripherally beyond said wound core member on each side thereof, and nonwound magnetic core members extending generally radially of said drum and disposed adjacent opposite sides of said wound core member along the axis of said drum, said non-Wound magnetic core members each having a radially outer end with an arcuate end face in close relation to the interior surface of the drum and extending along said interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said non-wound core members each having at the radially outer end thereof a circumferential dimension in the direction arcuately about the drum axis which greatly exceeds the corresponding dimension of said Wound core member over a radial depth of each non-wound core member inwardly from the arcuate end face thereof greatly exceeding the radial depth of said polar bar, said wound core member having a cross section which is substantially more greatly elongated in the plane transversely of the drum axis than in the plane parallel to the drum axis.

4. In a magnetic separator, a rotatable drum for receiving material to be separated at the top portion thereof and for retaining magnetic material therewith beyond the point where non-magnetic material falls from the drum, a base of magnetic material extending generally parallel to the axis of the drum but offset radially from said axis, a wound magnetic core member extending generally radially from said base across the drum axis and having an end terminating close to the drum periphery,

a winding on said wound core member, an arcuate polar bar secured to said end of said wound core member with an outer end face of said polar bar extending in close relation to the interior surface of said drum from a point generally adjacent the top of the drum to a point near the bottom of the drum, said polar bar extending peripherally beyond said wound core member on each side thereof, and non-wound magnetic core members extending generally radially from said base across the drum axis and disposed adjacent opposite sides of said wound core member along said base, said non-wound magnetic core members each having a radially outer end with an arcuate end face in close relation to the interior surface of the drum and extending along said interior surface of said drum firom a point generally adjacent the top of the drum to a point near the bottom of the drum, said non-wound core members each having at the radially outer end thereof a circumferential dimension in the direction arcuately about the drum axis which greatly exceeds the corresponding dimension of said wound core member over a radial depth of each nonwound core member inwardly from the arcuate end face thereof greatly exceeding the radial depth of said polar bar.

References Cited in the file of this patent UNITED STATES PATENTS 500,606 Payne July 4, 1893 802,170 Mofiatt Oct. 17, 1905 1,366,979 Ullrich Feb. 1, 1921 2,703,175 Becking v Mar. 1, 1955 FOREIGN PATENTS 423,650 Great Britain Feb. 5, 1935 

